Peach Sonker

Ingredients

• 4 cups (about 20 ounces) all-purpose flour
• 1/3 cup sugar, plus 1 tablespoon
• 4 teaspoons baking powder
• 1/2 teaspoon salt
• 8 tablespoons unsalted butter, cut into 1 tablespoon pieces
• 2 eggs
• 1 1/2 cups (about 12 ounces) whole milk
• 6 ripe medium peaches (about 2 pounds), sliced
• 2 tablespoons cornstarch
• 1/2 cup light brown sugar
• 1/2 teaspoon cinnamon
• 1/4 teaspoon nutmeg
• 3 tablespoons unsalted butter, cut into bits, plus more for greasing pan